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# Peter Perkins

### MathWorks

1,000 total contributions since 2011

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Splitting groups into seperate tables
MLE, it's not clear what you have done, and what you want to do. splitapply on a table is for cases when you want to apply a fu...

1 month ago | 0

How to account for the day suffix when using datetime to recognise dates in matlab?
Pedro, you could put a literal th in the format, 'eeee dd ''th''MMMM yyyy hh:mm:ss a' and read most of them, and go back and ...

1 month ago | 1

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How to plot datetime in garfh?
Gili, you say datetime and table, so I'm going to assume you are using those datatypes. contour does not currently support datet...

1 month ago | 0

Datetime from csv: format change from 2017b to 2018 and higher
readtable now reads timestamps as datetimes by default. I think you have two options: 1) If you are already getting datetimes i...

1 month ago | 0

Reassign Categorical Variable Value
If you wanted to all the sundays into mondays, it would be easy: combinecats. But you want to turn them into either mondays or f...

1 month ago | 0

Convert empty table to zero
The answer might be >> t = table.empty(0,3) t = 0×3 empty table >> t{1,:} = 0 t = 1×3 table Var1 Var2 Var3 ...

1 month ago | 0

How to create a datetime vector from text input and sum only certain values?

1 month ago | 0

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How to convert time to a number?
>> d = duration('17:15','Format','mm:ss') d = duration 17:15 >> d.Format = 'm' d = duration 17.25 min

2 months ago | 0

Is there a list of datastore SelectedFormats?
Somewhat buried in the tabularTextDatastore doc: "You can use the same conversion specifiers that the textscan function accepts"...

3 months ago | 0

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Problems with empty cell in a large matrix
You have a fixed-width file, and readtable needs to be told how it's organized, using fixedWidthImportOptions: >> opts = fixedW...

3 months ago | 1

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How to subset a table with character elements
Blue, I'm a little late to the party, but at least for those data, what you really ought to do is use a categorical for t.type. ...

3 months ago | 0

Tables and files in matlab

5 months ago | 1

How do I plot a datetime vs data within a cell array?
You almost certyainly do not want to store your data like that. For one thing, cell arrays are designed for complete generality,...

5 months ago | 0

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Pairwise difference of datetime vectors (i.e. pdist for time data)
pdist is probably much more than you actually need, assuming that by "distance" you mean a simple subtraction. pdist is designed...

5 months ago | 1

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Convert JSON datetime-wire-format
This appears to be some kind of weird mix of a text and a numeric representation that includes milliseconds since 1-Jan-1970 UTC...

5 months ago | 0

Devide a table in several tables by criteria
You can do this in several ways, but honestly the most straight-forward is to write a loop, as shown below. The real question is...

6 months ago | 1

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Two "Time" colunm in a time table
Correct, there is only one vector of times to label the rows of a timetable. But that's not to say you can't put both vectors in...

6 months ago | 0

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split timetables into multiple hourly timetables and save as separate .mat files
You can do this in several ways, but honestly the most straight-forward is to write a loop, as shown below. The real question is...

6 months ago | 0

Separating tables in tables after importing
Walter is correct, it's probaby not a good idea to split the table into separate workspace variables. And as he also says, it's ...

6 months ago | 0

time formate changes while exporting table as excel
S.M., are you quite sure this is not simply a formatting issue in the spreadsheet? When I run this code in a recent version of M...

6 months ago | 1

How to fix the missing patches that turn into NAT?
It's possible that what's happening is that your timestamps are stored in the spreadsheet file as text, not as dates, and that s...

6 months ago | 0

Bar plot using multiple table variables?
It's not completely clear what you are asking for, but my guess is that you want bar, with the 'stacked' input, and t{2:7,2:4} a...

6 months ago | 0

how to identify unique columns, based on the first two rows, make an average of the uniques columns and remove the duplicate columns?
You may have a reason for wanting row-oriented data, but I'm gonna suggest that you transpose your data, create a table, and use...

6 months ago | 0

How to pivot the table
At first glance, this seems like you could be using the unstack function, and it may be that you can. But you are a bit out of m...

6 months ago | 1

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Plotting two different dimensions time series data on the same x-axis
>> x1 = rand(1,6); t1 = datetime(2019,6,12,1:6,0,0,0); >> x2 = rand(1,24); t2 = datetime(2019,6,12,1,(0:23)*15,0); >> plot(t1,...

6 months ago | 0

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Creating a for loop to see if date exists
Also, it may be that you need to "find that date and find the position of where it is located" because you'll then use that loca...

6 months ago | 0

How to import text to timetable with ntsf timestamp
"it only accepts a number formated as uint64" NTFS timestamps are defined as 64bit numbers. Anything smaller than that and you ...

6 months ago | 0

How to ensure my times will follow daylight savings?
The answer is don't use datenums. They do not support time zomes at all. Use datetimes. If you set the TimeZone property on you...

6 months ago | 0

Round down to a chosen hour-min-sec time at a date
Since you're working in liear time (preserving dates) and no in circular time (caring only about time of day), I would think dis...

6 months ago | 0